This invention relates to liquid chromatography and, in particular, to disposable glass chromatography columns and apparatus to sealing same.
Liquid column chromatography is used for various different purposes. It may be employed to analyze, identify, extract, separate or purify sample components. The typical design consists of a surface-active powder or a size separating material such as a gel product, which is contained in the column. This is called the stationary phase. There is also a mobile phase that consists of a carrier fluid and a sample of the product to be analyzed, identified, extracted, separated or purified.
Liquid chromatography requires the use of different columns designs, depending on the application. Various materials are used in the manufacture of the cylinder used to house the packing media. Metallic cylinders are used to provide columns intended for high-pressure processes. The material most commonly used for the manufacture of this type of column is stainless steel. The columns are pre-packed and sealed with high pressure supporting gaskets. Glass and acrylic or plastic is employed in the manufacture of other cylinder designs.
The disadvantages of metallic columns are related to corrosion. For example, most organic solvents provide satisfactory results. Different results are obtained with long-termed contact with organic acids, halogenated hydrocarbons, and their by-products. Metallic columns are less resistant to the action of aqueous solutions of acids and salts commonly used in the reversed-phase chromatography, ion-exchange chromatography, and affinity and gel chromatography. Changes in the sample may also take place when metal is in contact with mixtures of sensitive biologically active compounds.
As disclosed in U.S. Pat. No. 4,968,421, issued to Spacek et al. on Nov. 6, 1990, glass columns have numerous advantages in liquid chromatography. One important advantage to the use of glass is the high resistance to the action of aggressive mobile phases or separated compounds. The high quality of the inner surface of a glass tube or column is also important because it reduces the spreading caused by the unevenness of the inner surface. This is a problem noted in columns manufactured with plastic materials or the like. The inner surface may suffer deformities and the spreading of the mobile phase becomes uneven. Glass also provides the possibility of visually observing the chromatographic separation and the quality of packing. Plastic columns possess a more opaque color and visualization of the process is not as clear as with a glass cylinder. Further, plastic is substantially less rigid than the glass which prevents or significantly deformation errors.
The disadvantages of glass columns for use in high-pressure chromatography, on the other hand, include the necessity of shaping the glass cylinder for the setting of secure sealing fittings, thus making the use of glass increasingly expensive when compared to other designs and materials. Designs using metallic jackets are complex apparatus and, therefore, do not offer a comparative advantage to steel columns because of cost. Thus, there is presently no disposable glass column that compares favorably in price to the use of plastic columns or steel columns for high-pressure applications.
U.S. Pat. No. 6,171,486 B1, issued to Green et al. on Jan. 9, 2001, discloses a liquid chromatography plastic cartridge with end caps. This invention describes a system that uses clamps, which are circumferentially located about the cartridge wall and seals by applying radial force. This is necessary since the plastic walls are flexible. The invention, as a result of the cylinder being fabricated with plastic, does not overcome difficulties associated with glass columns, nor does it contribute to designing a disposable column for such type of material.
U.S. Pat. No. 6,132,605, issued to Leavesley et al. issued on Oct. 17, 2000, discloses an apparatus for making a sealable connection to a plastic chromatography cartridge. In this invention, the sealing head or cap and its components are sized to fit by sliding into the cartridge. Once the cap and the elastomeric components are situated within the cartridge, axial compression forces on the elastomeric sealing members cause it to expand laterally and press against the cartridge forming a seal. This concept is applied to cartridges and employs a different technique than the present invention. It seals from inside and uses a cartridge as a column. Leavesley et al. does not resolve the issues addressed by the present invention, namely producing an economic and disposable glass column.
As noted above, Spacek et al. discloses a glass chromatography column. But the invention describes a system where the glass column is placed within a jacket. The jacket has threads on its ends and through axial forces closing sockets to seal the column by providing axial forces. The invention by Spacek et al. is not a disposable column since it is not advantageously economical to produce such system for single use.
The prior art does not disclose a closing system applicable to a glass chromatography column, which is simple and economic so as to provide a disposable unit. Moreover, it does not disclose a disposable glass column that compares favorably with the cost of plastic column and yet offers the advantages of glass.
It is an aspect of the invention to provide a chromatography column that is disposable.
Another aspect of the invention is to provide a chromatography column that utilizes a glass column and has the advantages inherent to such material as noted.
Still another aspect of the invention is provide a chromatography column that can be manufactured without requiring the ends of the glass tube to smooth or otherwise finished, i.e., the glass tube ends are merely rough cut.
It is another aspect of the invention to provide a chromatography column that is sealed with caps that placed under compression.
Another aspect of the invention is to provide a chromatography column that is translucent.
It is another aspect of the invention to provide a chromatography column that has a high chemical resistance.
Still another aspect of the invention is to provide a chromatography column that is assembled with simple made or readily available parts.
It is another aspect of the invention to provide a chromatography column that is readily adaptable to different sizes and packing materials so as to meet most chromatography applications.
Finally, it is an aspect of the invention to provide a chromatography column wherein the sealing caps can be adapted to various manifold configurations so that sorbents can be distributed evenly over the stationary phase materials contained within the column.
These and other aspects of the invention will become apparent in light of the detailed description of the invention which follows.
The invention is a disposable chromatography apparatus. A glass cylinder having top and bottom unfinished ends and internal diameter is provided. A top sealing cap having a sealing diameter and an integral manifold is provided. A top O-ring that is adapted to seal the top unfinished end of said glass cylinder is provided. A bottom sealing having an outlet and a sealing diameter is also provided. A bottom O-ring that is adapted to seal the bottom unfinished end of said glass cylinder is also provided. Wherein inserting said top sealing cap on the top unfinished end and inserting said bottom sealing cap on the bottom unfinished end and placing said caps under a compressive force so that said O-rings are urged against their respective unfinished ends, said apparatus is sealed.